This application claims the priority of Germany application 197 02 669.9-42 filed in Germany on Jan. 25, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a floor structure for a self-supporting motor-vehicle body, having a tunnel arrangement which extends in the longitudinal direction of the vehicle and is intended for receiving power-unit parts, and having a power-unit crossmember which supports individual power-unit parts, extends transversely over the open side of the tunnel arrangement and can be secured relative to the tunnel arrangement with the aid of a plurality of fastening points.
Such a floor structure is known from German Patent Document DE 24 35 545 B2. In the floor structure of the self-supporting motor-vehicle body there is formed, as a duct-like depression, a central tunnel which extends in the longitudinal direction of the vehicle. In the region of transition from the lateral tunnel walls to the horizontal floor structure, the mutually opposite tunnel walls are assigned reinforcement profiles, on which there is secured from beneath a power-unit crossmember for the purpose of supporting a gearbox arrangement comprising power-unit parts. In the event of impact loading on the motor-vehicle body in the transverse direction of the vehicle, the power-unit crossmember, which serves as a gearbox crossmember, can rupture in the region of its fastening points as a result of the high loading which occurs.
An object of the invention is to provide a floor structure of the type mentioned in the introduction which at least largely prevents rupturing of the power-unit crossmember.
This object is achieved according to preferred embodiments of the invention in that two mutually opposite supporting profiles are secured in a force-transmitting manner on the power-unit crossmember and each has a dimensionally rigid supporting leg which extends along a lateral tunnel wall of the tunnel arrangement, is arranged parallel to said tunnel wall, at a small distance therefrom, and--in relation to the longitudinal direction of the vehicle--extends at least over part of the length of the power-unit crossmember.
The provision of the rigid supporting profiles and the fact that these are secured on the power-unit crossmember in a force-transmitting manner means that forces which are exerted on the power-unit crossmember as a result of impact loading in the transverse direction of the vehicle no longer act exclusively on the fastening points, but rather are transmitted into the floor structure by virtue of the surface abutment of the supporting profiles against the respective lateral tunnel wall, this surface abutment taking place even if the floor structure is merely deformed to a small extent. This reliably prevents rupturing of the power-unit crossmember in the region of the fastening points. In addition, the supporting profiles also stiffen the tunnel arrangement as a whole.
The rigid supporting profiles can be secured on the power-unit crossmember in a force-transmitting manner by any type of known fastening means, provided that this force-transmitting connection is of higher strength than the attachment of the power-unit crossmember in the region of the fastening points on corresponding sections of the floor structure relative to the tunnel arrangement. The phrase "secured in a force-transmitting manner" thus means that the method of securing the supporting profiles on the power-unit crossmember has to be considerably stronger than the method of securing the power-unit crossmember relative to the tunnel arrangement.
The arrangement of the supporting legs parallel to the corresponding tunnel wall, and at a small distance therefrom, means that the surface abutment of the supporting legs against the respective tunnel wall, and thus surface pressure, is achieved even if the floor structure is merely deformed to a small extent. The feature of the supporting leg having to extend at least over a part of the length of the power-unit crossmember concerns the extent in the longitudinal direction of the vehicle, which is also designated as the width of the power-unit crossmember. The length must thus be dimensioned such that, rather than point loading, surface loading of the tunnel wall is obtained with appropriate deformation of the floor structure. A particularly preferred embodiment according to the invention provides a supporting-leg length which corresponds to the length of the power-unit crossmember--as seen in the longitudinal direction of the vehicle.
In one configuration of the invention, a front end side and a rear end side--in relation to the longitudinal direction of the vehicle--of each supporting leg are provided with a reinforcement flange which extends in the transverse direction of the vehicle. This further increases the rigidity of each supporting leg.
In a further configuration of the invention, a stiffening rib projects at right angles from each reinforcement flange and extends over the entire length of each reinforcement flange. This further increases the inherent rigidity of each supporting profile.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.